This invention relates to SiC-Al compound-ZrB.sub.2 composite sintered materials with improved erosion resistance to molten metals, particularly to molten steel.
High-melting metal oxides, such as alumina, magnesia and zirconia, have been used as a refractory material constituting members which are left immersed in, or kept in contact with, molten steel, such as nozzles, lining material, and blow pipes.
These refractory materials of the metal oxide type, however, are not satisfactory in mechanical properties, such as mechanical strength at high temperatures, creep characteristics and abrasion resistance, and suffer from short service lives, often causing erosion loss, breakage and other troubles during service.
Under such circumstances, it was attempted to use, in place of these metal-oxide refractories, silicon carbide and silicon nitride, which are richer in covalent bonding and show better mechanical properties at high temperatures, as described in Japanese Patent Application Laid-open No. 57-123916.
Structural members made of silicon carbide, although highly erosion-resistant against high temperature slag, tend to react with molten ferrous metals (such as molten steel) and oxides thereof, causing erosion loss, deposition of the ferrous metals or oxides thereof, and other troubles. Thus, the outstanding characteristics unique to silicon carbide have not been fully exhibited.